REFLECTOR: Re: Pictures of the air intake on my bird

["Brian K. Michalk" <michalk@sisko.awpi.com>]

> Air flow design is sometimes a bit mysterious without expensive analysis.
> Basically, you'd like to have the air enter your scoop (and it likes an
> airfoil shaped lip at the entrance), then expand and slow down in some
> uniform manner to convert dynamic to static pressure.  Then you can direct
> it where you want it, and then contract it again to convert static (what's
> left) back to dynamic pressure (speed) before having it re-enter the
> airstream.  This gives minimum drag.  Of course if you've heated it, it
> needs more area to exit then it needed to come in.

Hmmm, okay.
So let's assume that the stock scoop on the Velocity is more than
adequate for cooling.  This seems true since everyone's CHT's are quite
low.

Now we have this oversized scoop hanging out into the wind.  What
I'm really looking for is a device to lower my cooling and lower my
drag.  I'm not an aerodynamicist either, but it seems that seeing 
approximately 14 square inches (head on) of a ramp to go over, will
create less drag than 30 or so square inches of an intake where
the air is spilling back out over the sides.

When the air spills back out, does the intake create the same drag
as a flat plate of equivalent area being pulled through the air?

> You may like to get a second (or third, or fourth) opinion.  Specialists in
> this area will know more than I.

I think Alan Shaw knows a few things about this, but he has not
shown his face lately.  Is he on vacation or something?

There is almost no information on this subject that the
lay person can understand.  I'm not alone either.  There are
grumblings in the Rec.aviation.homebuilt newsgroup on how
everyone is always starting from scratch guessing at what
they think will work with absolutely no clue as to what they are
doing.  I'm in that group (haven't got a clue).

This would be a lot easier if we could see wind and how
it behaves.

Who remembers the Terminator movies where the bad guy was some
sort of liquid metal?  Man, all I could think of when I saw that
is how we could learn so much physics from such a property.
No only could we have transmissions in our cars that used an infinite
number of gear ratios, but we could test airfoils at will to
see what would work and what wouldn't.  I guess you could do
the same thing with computers, but that wouldn't be nearly as 
much fun.

-- 
Brian Michalk  <http://www.awpi.com/michalk>
Life is what you make of it ... never wish you had done something.
Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
musician, home-brewer, entrepenuer and SINGLE!